Diagnostic systems and methods of a continuously variable transmission

ABSTRACT

A diagnostic system of a vehicle for diagnosing a drive belt of a continuously variable transmission. A diagnostic circuit detects or predicts a fault of the drive belt based on an operating parameter received from a sensor associated with the vehicle during a predetermined diagnostic period.

RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/876,343, filed Jan. 22, 2018, which claims the benefit of U.S.Provisional Application No. 62/448,875, filed Jan. 20, 2017, titledDIAGNOSTIC SYSTEMS AND METHODS OF A CONTINUOUSLY VARIABLE TRANSMISSION,the entire disclosure of which is expressly incorporated by referenceherein.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to vehicle diagnostic systems,and more particularly to diagnostic systems for a drive belt used in acontinuously variable transmission (CVT).

BACKGROUND OF THE DISCLOSURE

Conventional vehicles, including utility vehicles and side-by-sidevehicles, have an internal combustion engine that generates drivetorque. To drive pistons of the engine, an air/fuel mixture combustswithin cylinders and the air/fuel mixture is regulated via intake andexhaust valves. The intake valves are selectively opened to draw airinto the cylinders, and the air is mixed with fuel to form the air/fuelmixture. To allow exhaust gas to exit from the cylinders aftercombustion, the exhaust valves are selectively opened at a specifictime.

Continuously variable transmissions (CVTs) are typically installed inrecreational vehicles, such as snowmobiles and all-terrain vehicles. TheCVT provides an infinite number of different gears that are effective attransmitting torque from the engine to an output driveline of thetransmission. The output driveline operatively couples the transmissionto at least one ground engaging member.

However, due to a belted construction of the CVT, one of the drawbacksis that a drive belt of the CVT tends to wear out and become damagedprematurely when the drive belt is not broken in properly or usedexcessively under undesirable conditions. Since the drive belt solelytransmits the engine power from a drive pulley to a driven pulley of theCVT, the drive belt is an important component of the CVT. Typically, theCVT drive belt is a V-belt, and is made from rubber, usuallyfiber-reinforced, that is rigid across but flexible along its length.During operation the drive belt undergoes extreme pressure and friction.

When the drive belt loses pressure between the sheaves of the CVT underhigh-load or over-load conditions, a slippage may occur causing beltdamage, such as a spin-burn or hour-glassing event. For example, duringthe spin-burn event, a belt temperature may rapidly reach over 200degrees Fahrenheit (° F.) without any warning, and may continue to riseup to 400° F. if no remedial action is taken. At that point, the drivebelt is irreparably damaged, and without replacing the damaged drivebelt, the vehicle cannot operate, thereby incurring increasedmaintenance costs and repair time.

As such, there are opportunities to develop an improved diagnosticsystem and method that can automatically detect or predict a fault ofthe drive belt before potential belt damage.

SUMMARY OF THE DISCLOSURE

As discussed in greater detail below, an exemplary diagnostic systemprovides an enhanced diagnostic function for detecting the fault of theCVT drive belt using various circuits and other related systems. In anexemplary diagnostic system and method the monitoring of the operatingparameters and the detecting the fault of the CVT drive belt areperformed automatically.

Also included in the present disclosure is a system and methodconfigured for monitoring patterns of operating parameter variationsduring a predetermined time period based on historical information of acomparative logic or algorithm. Further, the present diagnostic systemprovides enhanced displays and relations of the operating parameters inreal time. Additionally, the operating parameters are displayedautomatically without substantial manual interruptions. As a result, theoverall operational time of an engine system is enhanced withoutincurring additional operating expenses and maintenance costs.

In one exemplary embodiment, a vehicle diagnostic method of a vehicleincluding an internal combustion engine and a continuously variabletransmission (CVT) operatively coupled to the internal combustion engineis provided. The method comprising the steps of detecting at least oneengine crankshaft acceleration variation event of the vehicle using adetection circuit; determining at least one operating parameter receivedfrom one or more sensors associated with an operation of the CVT using amonitoring circuit; and determining based on the at least one operatingparameter when the at least one detected engine crankshaft accelerationvariation is related to a fault of the drive belt of the CVT using analert circuit. In one example, the diagnostic method further comprisesincluding an environmental condition parameter as the at least oneoperating parameter, wherein the environmental condition parameterincludes at least one of a fuel state signal, an engine coolanttemperature signal, a drive belt temperature signal, and a clutch statesignal. In another example, the diagnostic method further comprisesincluding an engine-based parameter as the at least one operatingparameter, wherein the engine-based parameter is related to at least oneof a crankshaft acceleration signal, an engine torque signal, and atransmission gear position signal. In a further example, the diagnosticmethod further comprises including a driveline-based parameter as the atleast one operating parameter, wherein the driveline-based parameter isrelated to at least one of a vehicle speed signal, an engine speedsignal, and a wheel speed signal. In still another example, thediagnostic method further comprises detecting the at least one enginecrankshaft acceleration variation event by measuring an acceleration ordeceleration rate of a crankshaft acceleration signal. In yet anotherexample, the diagnostic method further comprises detecting the at leastone engine crankshaft acceleration variation event based on a variationpattern of the operating parameter measured during a predetermined timeperiod. In a variation thereof, the diagnostic method further comprisesdetermining whether a frequency of the variation pattern is greater thana predetermined threshold. In another variation thereof the diagnosticmethod further comprises determining whether a pattern time period ofthe variation pattern is greater than a predetermined time period. In arefinement of the variation thereof the diagnostic method furthercomprises determining whether a magnitude of the variation pattern. In afurther example, the diagnostic method further comprises performing afirst correction method for determining whether the engine crankshaftacceleration variation event is caused by a belt slipping event or anengine combustion misfire event based on a single occurrence of the atleast one engine crankshaft acceleration variation event. In a yetfurther example, the diagnostic method further comprises performing asecond correction method for determining whether the engine crankshaftacceleration variation event is caused by a belt slipping event or anengine combustion misfire event based on a plurality of occurrences ofthe at least one engine crankshaft acceleration variation event.

In another exemplary embodiment, a vehicle diagnostic method of avehicle including an internal combustion engine and a continuouslyvariable transmission (CVT) operatively coupled to the internalcombustion engine is provided. The method comprising determining atleast one operating parameter received from one or more sensorsassociated with an operation of the CVT using a monitoring circuit;detecting at least one belt slipping event of a drive belt of the CVTusing a detection circuit; determining based on the at least oneoperating parameter when the at least one detected belt slipping eventis related to an impending fault of the drive belt of the CVT using analert circuit; and notifying the impending fault of the drive beltbefore belt or driveline damage of the vehicle occurs using the alertcircuit. In one example, the diagnostic method further comprisesgenerating an information signal related to the impending fault of thedrive belt. In another example, the diagnostic method further comprisesproviding an option to override a user input by adjusting at least onevalue of the at least one operating parameter. In a further example, thediagnostic method further comprises detecting the at least one beltslipping event by the detection circuit in at least one of a retroactivecontrol mode and an active control mode. In yet another example, thediagnostic method further comprises receiving a desired vehicle inputparameter using the monitoring circuit. In still another example, thediagnostic method further comprises including an environmental conditionparameter as the at least one operating parameter. In yet still anotherexample, the diagnostic method further comprises including anengine-based parameter as the at least one operating parameter. In yet afurther example, the diagnostic method further comprises including adriveline-based parameter as the at least one operating parameter. Instill yet a further example, the diagnostic method further comprisesdetecting the belt slipping event based on a comparison of anengine-based parameter and a driveline-based parameter for predictingthe impending fault of the drive belt. In a variation thereof, thediagnostic method further comprises determining whether at least one ofthe engine-based parameter and the driveline-based parameter is greaterthan a predetermined threshold. In a further still example, thediagnostic method further comprises informing the at least one detectedbelt slipping event using a display; and automatically adjusting the atleast one operating parameter based on a predetermined table.

In a further exemplary embodiment, a vehicle diagnostic method of avehicle including an internal combustion engine and a continuouslyvariable transmission (CVT) operatively coupled to the internalcombustion engine is provided. The method comprising the steps of:determining at least one operating parameter received from one or moresensors associated with an operation of the CVT using a monitoringcircuit; detecting at least one critical belt life event of a drive beltof the CVT using a detection circuit; determining based on the at leastone operating parameter when the at least one detected critical beltlife event is related to a fault of the drive belt of the CVT using analert circuit; and generating an information signal related to a life ofthe drive belt using the alert circuit. In an example, the diagnosticmethod further comprises including an environmental condition parameteras the at least one operating parameter, wherein the environmentalcondition parameter includes a temperature signal. In a further example,the diagnostic method further comprises including an engine-basedparameter as the at least one operating parameter, wherein theengine-based parameter is related to at least one of an engine loadsignal, a throttle position signal, an engine torque signal, and anengine power signal. In yet a further example, the diagnostic methodfurther comprises including a driveline-based parameter as the at leastone operating parameter, wherein the driveline-based parameter isrelated to at least one of a vehicle speed signal and an engine speedsignal. In still a further example, the diagnostic method furthercomprises detecting the critical belt life event based on a comparisonof an engine-based parameter, a driveline-based parameter, and anenvironmental condition parameter; and predicting a remaining life ofthe drive belt based on the comparison. In a variation thereof, thediagnostic method further comprises determining whether the remaininglife of the drive belt is less than a predetermined threshold. Inanother variation thereof, the diagnostic method further comprisesdisplaying the information signal on a display using a textual orgraphical indicator associated with the remaining life of the drivebelt. In another example, the diagnostic method further comprisesadjusting at least one of an engine-based parameter, a driveline-basedparameter, and an environmental condition parameter based on the atleast one detected critical belt life event.

In a further exemplary embodiment of the present disclosure, a vehiclediagnostic method of a vehicle including an internal combustion engineand a continuously variable transmission (CVT) operatively coupled tothe internal combustion engine is provided. The method comprising thesteps of: determining an amount of input energy provided to the CVT bythe internal combustion engine; determining an amount of output thermalenergy leaving the CVT; determining based on the amount of input energyand the amount of output thermal energy an amount of accumulated energyin the CVT; comparing the amount of accumulated energy to a threshold;and reducing the amount of input energy in response to the amount ofaccumulated energy satisfying the threshold. In an example thereof, thestep of reducing the amount of input energy includes the step ofreducing the power provided by the internal combustion engine to theCVT. In another example, the amount of input energy is determined basedon mechanical input characteristics to the CVT. In yet another example,the amount of output thermal energy is determined based on fluidcharacteristics of the CVT. In still another example, the step ofdetermining the amount of input energy provided to the CVT by theinternal combustion engine includes the steps of: determining an outputpower of the internal combustion engine; determining a CVT clutchefficiency based on the determined output power; and determining theamount of input energy provided to the CVT based on the determinedoutput power and the determined CVT clutch efficiency. In a variationthereof, the step of determining the CVT clutch efficiency based on thedetermined output power includes the step of retrieving from a databasethe determined CVT clutch efficiency. In yet still another example, thestep of determining the amount of output thermal energy leaving the CVTincludes the steps of: determining an air temperature of air entering aninterior of the CVT; and determining the amount of output thermal energyleaving the CVT based on a CVT clutch airflow model, a heat transfercoefficient, and the determined air temperature.

In a yet further exemplary embodiment of the present disclosure, avehicle diagnostic method of a vehicle including an internal combustionengine and a continuously variable transmission (CVT) operativelycoupled to the internal combustion engine. The method comprising thesteps of: detecting a plurality of engine crankshaft accelerationvariation events; determining a frequency of the plurality of enginecrankshaft acceleration variation events; determining a CVT beltinteraction frequency of a drive belt of the CVT; and classifying theplurality of engine crankshaft acceleration variation events as one ofan engine misfire event and a CVT belt damage event based on acomparison of the frequency to the CVT belt interaction frequency. In anexample thereof, the step of determining the CVT belt interactionfrequency of the drive belt of the CVT includes the steps of:determining a pitch diameter of a drive clutch of the CVT; determining alinear speed of the drive belt of the CVT based on the determined pitchdiameter of the drive clutch and a rotational speed of a drive shaft ofthe CVT; and determining the CVT belt interaction frequency of the drivebelt based on the determined linear speed of the drive belt of the CVTand a length of the belt.

Additional features and advantages of the present disclosure will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the illustrative embodiment exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be more readily understood in view of the followingdescription when accompanied by the below figures and wherein likereference numerals represent like elements, wherein:

FIG. 1 illustrates a representative view of a drive train of anexemplary side-by-side vehicle;

FIG. 2 illustrates a representative view of initial air flow to anexemplary continuous variable transmission (CVT);

FIG. 3 illustrates an exemplary block diagram and schematic view of oneillustrative embodiment of a diagnostic system having an engine controlcircuit and a diagnostic circuit;

FIG. 4 illustrates an exemplary processing sequence of executing thepresent diagnostic system for detecting a belt slipping event in aretroactive control mode;

FIG. 5 illustrates an exemplary processing sequence of executing thepresent diagnostic system for detecting the belt slipping event in aproactive control mode;

FIG. 6 illustrates an exemplary processing sequence of executing thepresent diagnostic system for detecting a critical belt life event;

FIG. 7 illustrates an exemplary processing sequence of executing thepresent diagnostic system for detecting an engine misfire event;

FIG. 8 illustrates an exemplary processing sequence of executing thepresent diagnostic system for detecting an engine misfire event or andamaged belt event;

FIG. 9 illustrates an exemplary processing sequence of determining ainteraction frequency of the CVT belt;

FIG. 10 illustrates an exemplary processing sequence of regulating peakoutput power of a power source based on accumulated energy in a CVT;

FIG. 11 illustrates an exemplary processing sequence for determining anamount of energy input into a CVT during operation of the CVT; and

FIG. 12 illustrates an exemplary processing sequence for determining anamount of energy exiting a CVT during operation of the CVT.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of the present disclosure, the drawings are not necessarilyto scale and certain features may be exaggerated in order to betterillustrate and explain the present disclosure. The exemplifications setout herein illustrate an exemplary embodiment of the disclosure, in oneform, and such exemplifications are not to be construed as limiting thescope of the disclosure in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

The embodiments disclosed below are not intended to be exhaustive or tolimit the invention to the precise forms disclosed in the followingdetailed description. Rather, the embodiments are chosen and describedso that others skilled in the art may utilize their teachings. While thepresent disclosure is primarily directed to a continuously variabletransmission (“CVT”), it should be understood that the featuresdisclosed herein may be incorporated into one or more vehicles.Exemplary vehicles include all-terrain vehicles, side-by-side UTVs,utility vehicles, motorcycles, snowmobiles, golf carts, and othervehicles or devices incorporating a continuously variable transmission.

Referring now to FIG. 1, a representative view of a vehicle 100 isshown. Vehicle 100 as illustrated includes a plurality of groundengaging members 102. Illustratively, ground engaging members 102 arewheels 104 with associated tires. Other exemplary ground engagingmembers include skis and tracks. In one embodiment, one or more of thewheels may be replaced with tracks, such as the Prospector II Tracksavailable from Polaris Industries, Inc. located at 2100 Highway 55 inMedina, Minn. 55340.

One or more of ground engaging members 102 are operatively coupled to ashiftable transmission 130 to power the movement of vehicle 100. Othersuitable types of transmission, such as non-shiftable gear sets, arealso contemplated. Exemplary power sources 106 include internalcombustion engines and electric motors. In the illustrated embodiment,the power source 106 is an internal combustion engine.

An internal combustion power source 106 is represented in FIG. 1. Powersource 106 receives fuel from a fuel source 108 and ambient air from anair intake system 110. For example, the ambient air is selectivelysupplied to the power source 106 to be mixed with the fuel for internalcombustion. Exhaust is expelled from power source 106 through an exhaustsystem 112. An output shaft 120 of power source 106 is coupled to adrive member of a continuously variable transmission (“CVT unit”) 122. Adriven member of the CVT unit 122 is operatively coupled to the drivemember of the CVT unit 122 through a drive belt. CVT unit 122 receivesambient air through an air intake system 124 and expels air from aninterior of CVT unit 122 through an exhaust system 126. The drivenmember is coupled to an output shaft 128 which is operatively coupled toan input of a shiftable transmission 130.

A first output shaft 132 of shiftable transmission 130 is coupled to arear drive unit 134. Rear drive unit 134 is coupled to correspondingwheels 104 of a rear axle 136 through half shafts 138. Rear drive unit134 may be a differential. A second output shaft 140 of shiftabletransmission 130 is coupled to a front drive unit 142. Front drive unit142 is coupled to corresponding wheels 104 of a front axle 144 throughhalf shafts 138. Front drive unit 142 may be a differential.

Various configurations of rear drive unit 134 and front drive unit 142are contemplated. Regarding rear drive unit 134, in one embodiment reardrive unit 134 is a locked differential wherein power is provided toboth of the wheels of axle 136 through output shafts 150. In oneembodiment, rear drive unit 134 is a lockable/unlockable differentialrelative to output shafts 150. When rear drive unit 134 is in a lockedconfiguration power is provided to both wheels of axle 136 throughoutput shafts 150. When rear drive unit 134 is in an unlockedconfiguration, power is provided to one of the wheels of axle 136, suchas the wheel having the less resistance relative to the ground, throughoutput shafts 150. Regarding front drive unit 142, in one embodimentfront drive unit 142 has a first configuration wherein power is providedto both of the wheels of front axle 144 and a second configurationwherein power is provided to one of the wheels of axle 144, such as thewheel having the less resistance relative to the ground.

In one embodiment, front drive unit 142 includes active descent control(“ADC”). ADC is a drive system that provides on-demand torque transferto the front wheels when one of the wheels 104 of rear axle 136 losetraction and that provides engine braking torque to the wheels 104 offront axle 144. Both the on-demand torque transfer and the enginebraking feature of front drive unit 142 may be active or inactive. Inthe case of the on-demand torque transfer, when active, power isprovided to both of the wheels of front axle 144 and, when inactive,power is provided to one of the wheels of front axle 144. In the case ofthe engine braking, when active, engine braking is provided to thewheels of front axle 144 and, when inactive, engine braking is notprovided to the wheels of front axle 144. Other suitable arrangementsare contemplated for a two wheel drive system to suit the application.Exemplary front drive units are disclosed in U.S. patent applicationSer. No. 12/816,052, filed Jun. 15, 2010, titled ELECTRIC VEHICLE, U.S.Pat. No. 5,036,939, and U.S. Pat. No. RE38,012E, the disclosures ofwhich are expressly incorporated herein by reference.

In one embodiment, one or more of CVT unit 122, air intake system 124,and exhaust system 126 includes a sensor 160 which monitors acharacteristic of the air within the interior of the respective CVT unit122, air intake system 124, and exhaust system 126. In the illustratedembodiment, multiple sensors 160 are operatively and communicablyconnected to the transmission 130, the wheel 104, the air intake system124, the exhaust system 126, and the CVT unit 122 for receiving signalsfrom at least one of the connected sensors. Exemplary sensors include atemperature sensor, a speed sensor, and a load sensor. In oneembodiment, sensors 160 provide an indication of a temperature of theair within the interior of the respective CVT unit 122, air intakesystem 124, and exhaust system 126 to an engine control circuit (ECC)162 which includes logic to control the operation of power source 106.When a monitored air temperature exceeds a threshold amount, ECC 162responds by at least one of limiting an output speed of output shaft 120of power source 106, limiting a speed of vehicle 100, and indicating anoverheat condition to an operator of vehicle 100 through a userinterface, such as a gauge 164 or display 165, within an operator areaof vehicle 100. Exemplary user interfaces are disclosed in U.S. patentapplication Ser. No. 15/161,720, filed May 23, 2016, titled DISPLAYSYSTEMS AND METHODS FOR A RECREATIONAL VEHICLE, the entire disclosure ofwhich is expressly incorporated by reference. Exemplary indicators of anoverheat condition include a light, a warning message on a display 165,and other suitable ways of communicating a condition to an operator. Bylimiting an engine speed or a vehicle speed, the temperature of the airin an interior of CVT unit 122 is reduced and a temperature of a drivebelt in the interior of CVT unit 122 is reduced. This reduces the riskof a drive belt failure.

Referring to FIG. 2, an exemplary continuously variable transmission 200is represented. Continuously variable transmission 200 includes a driveclutch 202 operatively coupled to output shaft 120, a driven clutch 204operatively coupled to output shaft 128, and a drive belt 206operatively coupled to drive clutch 202 and driven clutch 204 totransfer power from drive clutch 202 to driven clutch 204. Drive clutch202 includes a first drive clutch sheave 208 and a second drive clutchsheave 210 moveable relative to the first drive clutch sheave 208.Driven clutch 204 includes a first driven clutch sheave 212 and a seconddriven clutch sheave 214 moveable relative to the first driven clutchsheave 212.

Both of drive clutch 202 and driven clutch 204 are positioned within ahousing 220 having an interior 222. Housing 220 may be comprised ofmultiple components which cooperate to form housing 220. The multiplecomponents may also include features to direct air flow through interior222 of housing 220. In one example, housing 220 includes a base having afirst opening adapted to receive the drive shaft 120 and a secondopening adapted to receive the driven shaft 128 and a cover coupled tothe base. The cover and the base cooperating to define interior 222 ofthe housing 220. The cover and base may include features to direct airflow through interior 222 of housing 220.

As represented in FIG. 2, one or more air supply conduits 230 arecoupled to housing 220. Exemplary air supply conduits include hoses. Inone embodiment, each air supply conduit 230 provides air to the interior222 of housing 220 through a respective air supply opening 232 in anexterior 234 of housing 220. The air supply conduits 230 provide air tothe interior 222 of housing 220 to cool drive clutch 202, driven clutch204, and drive belt 206. As a result, this configuration provides acooling effect on the drive belt 206. The supplied air is directedtowards one or more of first drive clutch sheave 208, second driveclutch sheave 210, first driven clutch sheave 212, and second drivenclutch sheave 214 whereat, the supplied air will take on heat to coolthe respective one or more of first drive clutch sheave 208, seconddrive clutch sheave 210, first driven clutch sheave 212, and seconddriven clutch sheave 214. The air will then circulate within interior222 of housing 220 potentially or intentionally contacting one or moreof first drive clutch sheave 208, second drive clutch sheave 210, firstdriven clutch sheave 212, and second driven clutch sheave 214 and thenexiting interior 222 of housing 220 through one or more air exhaustopenings 236 in wall 234 of housing 220. One or more exhaust or outletconduits 238 are coupled to the exhaust openings 236.

Referring now to FIG. 3, an exemplary schematic view of a diagnosticsystem 300 is shown. Included in the diagnostic system 300 is the enginecontrol circuit (ECC) 162 having a diagnostic circuit (DC) 302. The DC302 is configured to detect or predict a fault of the drive belt 206 ofthe CVT 122 based on at least one operating parameter, such as an engineor vehicle parameter or signal. Although the DC 302 is shown inside theECC, the DC may be independent or separate from the ECC or incorporatedinto any other systems of the vehicle 100 to suit the application.

The fault of the drive belt 206 may refer to a deteriorating conditionof the drive belt caused by the spin-burn or hour-glassing event. Forexample, during a substantial rotation of the drive sheaves relative tothe near stationary drive belt, a slip in the drive belt 206 may createthe hour-glassing event, changing side profiles of the drive belt 206into an hour-glass shape. As an example only, when the wheels 104 arestuck in a ditch or a loose soil, such as mud or snow, an engine speedmay increase but a wheel speed may decrease down to almost zero. Suchlack of rotational movement of the wheels 104 may cause the driven shaft128 to stop and cause the hour-glassing event on the drive belt 206.

In the illustrated embodiment, the DC 302 is microprocessor-based andincludes a non-transitory computer readable medium or database 304 whichincludes processing instructions stored therein that are executable bythe microprocessor of DC 302 to control operation of a diagnosticprocess of the CVT 122. A non-transitory computer-readable medium, ormemory, may include random access memory (RAM), read-only memory (ROM),erasable programmable read-only memory (e.g., EPROM, EEPROM, or Flashmemory), or any other tangible medium capable of storing information.For example, a predetermined calibration or empirical lookup table maybe stored on a volatile or non-volatile memory for subsequent access.

Exemplary operating parameters relate to an engine speed (e.g.,revolutions per minute (RPM)), an engine load (e.g., units of percentagerelative load (% RL)), a throttle position (e.g., a throttle positionpercentage), an engine torque (e.g., inch-pounds or inch-ounces), anengine power and the like. Other suitable operating parameters are alsocontemplated to suit different applications. Detailed descriptions ofexemplary operating parameters and signals are provided below inparagraphs relating to FIGS. 4-7.

As used herein, the term “circuit” or “unit” may refer to, be part of,or include an Application Specific Integrated Circuit (ASIC), anelectronic circuit, a processor or microprocessor (shared, dedicated, orgroup) and/or memory (shared, dedicated, or group) that executes one ormore software or firmware programs, a combinational logic circuit,and/or other suitable components that provide the describedfunctionality. Thus, while this disclosure includes particular examplesand arrangements of the circuits, the scope of the present system shouldnot be so limited since other modifications will become apparent to theskilled practitioner.

The term “logic” as used herein includes software and/or firmwareexecuting on one or more circuits. Therefore, in accordance with theembodiments, various logic may be implemented in any appropriate fashionand would remain in accordance with the embodiments herein disclosed. Anon-transitory machine-readable medium comprising logic can additionallybe considered to be embodied within any tangible form of acomputer-readable carrier, such as solid-state memory, magnetic disk,and optical disk containing an appropriate set of computer instructionsand data structures that would cause a processor to carry out thetechniques described herein.

This disclosure contemplates other embodiments in which the DC 302 isnot microprocessor-based, but rather is configured to regulate operationof the diagnostic process of the CVT 122 based on one or more sets ofhardwired instructions and/or software instructions stored in thedatabase 304. Further, the DC 302 may be contained within a singledevice or be a plurality of devices networked together to provide thefunctionality described herein.

During the diagnostic process, the DC 302 regulates an overalldiagnostic operation of the present system 300. In general, the DC 302monitors at least one of the operating parameters or signals fordiagnosing the drive belt 206 of the CVT 122 via a network 306, such asa controller area network (CAN) bus. Any type of network having acollection of networkable devices, such as computers, servers, and otherhardware interconnected by communication channels is contemplated.Exemplary networks include wired or wireless networks or combinationsthereof. Exemplary networks may include Bluetooth enabled networks orWi-Fi enabled networks.

Also included in the diagnostic system 300 are one or more sensors 160,such as a throttle position sensor 308, an engine torque sensor 310, atemperature sensor 312, an engine load sensor 314, a vehicle speedsensor 316, an engine RPM sensor 318, a fuel sensor 320, and the like.Such sensors 160 are operatively connected to the DC 302 via the network306 using the user interface, such as the gauge 164 or display 165, andconfigured for measuring operating characteristics and conditions of thevehicle 100. During operation, related information of the operatingparameters or signals is displayed on the display 165 accessible to auser via the network 306. It is contemplated that the user may refer toan operator or any other system associated with the diagnostic system300. The DC 302 manages interactions between the user and the DC 302 byway of a human machine interface (HMI), such as a gauge interface, akeyboard, a touch sensitive pad or screen, a mouse, a trackball, a voicerecognition system, and the like. The display 165 (e.g., textual andgraphical) is configured for receiving an input data from the userand/or the DC 302.

In one embodiment, the user uses an input device, such as the HMI, tographically or textually interact with the present system 300.Associated data and/or parameters are generally received in the DC 302and then transferred to the display 165 via a dedicated or sharedcommunication system via the network 306. Further, any collaborative orthird-party database reachable by the DC 302 can also be used as part ofthe diagnostic system 300.

Referring now to FIG. 3, it is preferred that the DC 302 includes amonitoring circuit 322, a detection circuit 324, an alert circuit 326, astoring circuit 328, and a display circuit 330. Although thesesub-circuits 322-330 are illustrated as children circuits subordinate ofthe parent circuit DC 302, each sub-circuit can be operated as aseparate unit from the DC, and other suitable combinations ofsub-circuits are contemplated to suit different applications. One ormore circuits or units can be selectively bundled as a key softwaremodel running on the processor having software as a service (SSaS)features.

All relevant information can be stored in the database 304, e.g., as anon-transitory data storage device and/or a machine readable datastorage medium carrying computer-executable instructions, for retrievalby the DC 302 and its children circuits. Also included in the DC 302 isan interface circuit 332 for providing an interface between the DC 302,the database 304, the network 306, the sensors 160, and the display 165of the vehicle 100. It is preferred that the interface circuit 332provides electrical interconnections for performing diagnostic operationof, for example, the network 306, the display 165, and other relatedsystem devices, services, and applications.

The other devices, services, and applications may include, but are notlimited to, one or more software or hardware components, etc., relatedto the DC 302. The interface circuit 332 also receives operating data orparameters related to the vehicle 100 from the sensors 160 or otherrelated systems, which are communicated to the respective circuits, suchas the DC 302, and its children circuits.

The monitoring circuit 322 is configured to receive the operating dataand parameters via the interface circuit 332, and provide operatingcondition or characteristic information about the vehicle 100.Specifically, the monitoring circuit 322 provides detailed informationof the engine or vehicle conditions, such as temperature, speed andpower of the vehicle 100, relative to the CVT 122 using the sensors 160.In general, as discussed in greater detail below, diagnostic system 300assesses its operational characteristics by evaluating the engine orvehicle operating conditions.

The detection circuit 324 is configured to receive the operating dataand parameters from the network 306 via the interface circuit 332, andto examine the received operating data and parameters for diagnosing thedrive belt 206 based on a predetermined set of rules or algorithms.During operation, the detection circuit 324 recognizes or identifies apredetermined triggering event caused by a condition change of the CVT122, the power source 106, and/or the vehicle 100, and identifies ordetects the fault of the drive belt 206 based on the triggering event.Exemplary triggering events are described in paragraphs below relatingto FIGS. 4-7.

The alert circuit 326 is configured to generate an information signal ormessage INFO to inform the user or other users of the detectedtriggering event by converting the triggering event into a meaningfulmessage recognizable by the user. More specifically, one or moretriggering events are transformed by the alert circuit 326 into warningor status signals of the drive belt 206. Subsequently, the warning orstatus signals are delivered to the display 165, a mobile device, or anyother computing device to alert the user or other users. It is alsocontemplated that when the triggering event is detected, the alertcircuit 326 provides an option to override the user input by adjustingone or more values of the operating parameters to prevent damage to thedrive belt 206, thereby alleviating the triggering event. Exemplaryinformation signals are described in paragraphs below relating to FIGS.4-7. In one embodiment a user input is provided to opt out of one ormore processing sequences disclosed herein to provide operatorflexibility of vehicle performance.

The storing circuit 328 is configured to digitally store relevantinformation related to the present diagnostic system 300 in the database304. More specifically, the database 304 includes the operating data andparameters related to analysis data about the triggering events for thepurposes of research, development, improvement of the comparative logicor algorithms and further investigations by the user or the relatedsystems.

The display circuit 330 is configured to retrieve from the database 304and interactively display an appropriate status or information messageassociated with the information signal INFO generated based on thetriggering event for illustration on the display 165. An instance reportrelated to each information signal INFO and the corresponding triggeringevent is graphically or textually generated by the display circuit 330in real time. In one embodiment, the information is automaticallytransmitted to a central server, other vehicles, or any other suitablesystems, as desired.

Referring now to FIGS. 4-7, exemplary processing sequences of executingthe present diagnostic system 300 is illustrated. Although the followingsteps are primarily described with respect to the embodiments of FIGS.1-3, it should be understood that the steps within the processingsequences may be modified and executed in a different order or sequencewithout altering the principles of the present disclosure.

FIG. 4 illustrates an exemplary processing sequence of a belt slippingevent detection logic 400 of the diagnostic system 300 in a retroactivecontrol mode. The belt slipping event is one of the triggering eventsdetected by the detection circuit 324. In the retroactive control mode,when the belt slipping event is detected, the alert circuit 326 has anoption to notify the user of the fault of the drive belt 206, orautomatically adjust at least one operating parameter to remove orlessen the effect of the fault for continuous operation of the vehicle100 without interruption.

In the illustrated embodiment, steps 402 and 404 are performedsimultaneously, but each step may be performed separately orindividually independent from each other. In step 402, the monitoringcircuit 322 receives a desired vehicle input signal or parameter fromthe user, such as a predetermined throttle position parameter, foropening and closing a throttle control valve, from the throttle positionsensor 308, or a predetermined engine torque parameter from the enginetorque sensor 310.

In step 404, the monitoring circuit 322 receives an environmentalcondition parameter or signal from the vehicle 100, such as atemperature signal from the temperature sensor 312 configured to measuretemperature of the drive belt 206 or air temperature of the CVT 122. Forexample, the temperature sensor 312 may be disposed in the air supplyconduit 230, the air exhaust conduit 238, or directly on or near thedrive belt 206 using an infrared sensor. Other exemplary environmentalcondition signals include an engine manifold temperature, pressure orvacuum signal, a motion signal, a crankshaft acceleration signal, atransmission gear position signal, a CVT reduction rate signal, adriveline strain or torque signal, a steering angle signal, a steeringrack displacement signal, and the like.

Additional suitable environmental condition signals are alsocontemplated as needed. For example, in another embodiment, themonitoring circuit 322 may receive a road load condition, such as a hardground condition, a loose sandy condition, and the like, by detectingthe road load condition using the sensor 160 or receiving the road loadcondition inputted by the user for applying the road load condition asone of the environmental condition signals.

It is preferred that steps 406 and 408 are performed simultaneously, buteach step may be performed separately or individually independent fromeach other. In step 406, the monitoring circuit 322 receives andmonitors at least one engine-based parameter, such as an engine loadsignal (e.g., % RL) from the engine load sensor 314, a throttle positionsignal (e.g., a throttle position percentage) from the throttle positionsensor 308, or an engine torque signal (e.g., inch-pounds orinch-ounces) from the engine torque sensor 310. Other exemplaryengine-based parameters include an engine power parameter, atransmission speed parameter, a crankshaft rotation or positionparameter, an engine control unit (ECU) internal clock parameter, acrankshaft acceleration parameter, and the like, as received from eachcorresponding sensor 160.

In step 408, the monitoring circuit 322 monitors at least onedriveline-based parameter, such as a vehicle speed parameter (e.g.,miles/hour) from the vehicle speed sensor 316 or an engine speedparameter (e.g., RPM) from the engine speed sensor 318. Other exemplarydriveline-based parameters include parameters received from an infraredsensor, a global positioning system sensor, a laser sensor, anultrasonic sensor, a steering angle sensor, a steering rack displacementsensor, a gear position sensor, and the like. Other suitablechassis-based parameters are also contemplated to suit the application.

In step 410, the detection circuit 324 detects the belt slipping eventbased on a comparison of at least one of the engine-based anddriveline-based parameters with a predetermined threshold for preventingdamage related to the drive belt 206 of the CVT 122 or an outputdriveline of the transmission 130. Any combinations of the engine-basedand driveline-based parameters are considered to detect the beltslipping event. For example, when a rotational speed ratio between thedrive shaft 120 and the driven shaft 128 is 4:1 and an engine load is at10-20% for a predetermined time period, e.g., 5 seconds, then the beltslipping event is suspected. As another example, when the rotationalspeed ratio between the drive shaft 120 and the driven shaft 128 is 7:1and the engine load is at approximately 50% or greater for apredetermined time period, e.g., 1 second, then the belt slipping eventmay be in progress. When the at least one of the engine-based anddriveline-based parameter is greater than the predetermined threshold,control proceeds to at least one of step 412 and step 414 depending onthe application. Otherwise, control returns to steps 402 and 404.

For example only, the belt slipping event F (slip) may be defined by afunction of time and at least one of the engine-based anddriveline-based parameters, as provided by expression (1):F(slip)=T·Parm  (1)

wherein T denotes a time period and Parm denotes the at least one of theengine-based and driveline-based parameters. As an example, the beltslipping event may be detected by the detection circuit 324 when theengine RPM and the driveline speed parameters exceeding thepredetermined threshold continue for a predetermined time period whilethe vehicle 100 is in a park or neutral position. An exemplary timeperiod may range from 1 second to 5 seconds.

It is preferred that steps 412 and 414 are performed simultaneously, buteach step may be performed separately or individually independent fromeach other. In step 412, the alert circuit 326 generates the informationsignal INFO based on the detected triggering event, the belt slippingevent, to inform the user of the triggering event using the display 165.For example, the information signal INFO is displayed using a dashboardlight or an audible signal including a textual or graphical indicator(e.g., a symbol or icon) on the display 165. Other suitable audio,visual, or tactile indicators are also contemplated.

In step 414, the alert circuit 326 automatically adjusts or modifies atleast one of the operating parameters based on a predeterminedcalibration or empirical lookup table 334 stored in the database 304,such as the desired vehicle input parameters, the environmentalcondition parameters, the engine-based parameters, or thedriveline-based parameters, to prevent or lessen the potential CVT ordriveline damage. For example, when the detection circuit 324 identifiesthe belt slipping event, the alert circuit 326 automatically reduces theengine speed, the engine torque, the engine load, or the throttleposition percentage, by a predetermined value. Other suitableadjustments or modifications of the operating parameters arecontemplated to suit different applications. In one embodiment, theautomatic adjustment step may be optionally turned ON or OFF as desired,and a progressive warning system may be utilized to gradually warn theuser of the potential CVT or driveline damage using a color, hue, andsaturation intensity technique. For example, a yellow light may indicatea low level warning suggesting the user to change to a lower gear, but ared light may indicate a high level warning automatically reducing theengine load or speed to a predetermined value.

FIG. 5 illustrates an exemplary processing sequence of the belt slippingevent detection logic 500 of the diagnostic system 300 in a proactivecontrol mode. In the proactive control mode, the diagnostic system 300proactively notifies the user of an impending fault of the drive belt206 or automatically adjusts at least one of the operating parametersbefore the potential CVT or driveline damage occurs. For example, whenthe diagnostic system 300 determines that a probability of having thefault is approaching approximately 90%, the alert circuit 326automatically adjusts the at least one operating parameter to remove orlessen the effect of the impending fault of the vehicle 100 withoutinterruption.

In the illustrated embodiment, it is preferred that steps 502, 504, and506 are performed simultaneously, but each step may be performedseparately or individually independent from each other. In step 502, themonitoring circuit 322 receives the desired vehicle input signal orparameter from the user. In step 504, the monitoring circuit 322receives the environmental condition parameter or signal from thevehicle 100. In step 506, the monitoring circuit 322 monitors the atleast one driveline-based parameter.

In step 508, the detection circuit 324 detects the belt slipping eventbased on the comparison of at least one of the user desired vehicleinput signal, the environmental condition signal, and thedriveline-based parameter with the predetermined threshold forpredicting potential damage related to the drive belt 206 of the CVT 122or the output driveline of the transmission 130. Any combinations of theuser desired vehicle input signal, the environmental condition signal,and the driveline-based parameter are considered to detect the beltslipping event. For example, when a desired throttle position percentageis at 20%, a rotational speed ratio between the drive shaft 120 and thedriven shaft 128 is 4:1, and an engine load is at 10-20% for apredetermined time period, e.g., 5 seconds, then the belt slipping eventis likely to occur. As another example, when the desired throttleposition percentage is at 50%, the rotational speed ratio between thedrive shaft 120 and the driven shaft 128 is 7:1, and the engine load isat approximately 50% or greater for a predetermined time period, e.g., 1second, then the belt slipping event may be imminent. When a probabilityof having the fault of the drive belt 206 is greater than apredetermined threshold (e.g., 90%), control proceeds to at least one ofstep 510 and step 512 depending on the application. Otherwise, controlreturns to steps 502, 504, and 506.

It is preferred that steps 510 and 512 are performed simultaneously, buteach step may be performed separately or individually independent fromeach other. In step 510, the alert circuit 326 generates the informationsignal INFO based on the detected belt slipping event to inform the userof the impending fault of the drive belt 206 before potential belt ordriveline damage occurs. Similarly, in step 512, the alert circuit 326automatically adjusts or modifies at least one of the operatingparameters before the impending fault of the drive belt 206 to preventor lessen the potential CVT or driveline damage. For example, the alertcircuit 326 automatically reduces the throttle position percentage by apredetermined rate (e.g. 10% thereby reducing the throttle positionpercentage from 50% to 40%) to avoid the impending fault of the drivebelt 206.

FIG. 6 illustrates an exemplary processing sequence of a critical beltlife event detection logic 600 of the diagnostic system 300. Thecritical belt life event is one of the triggering events detected by thedetection circuit 324, and is triggered based on a temperature parameterrelated to the drive belt 206 of the CVT 122.

Based on the temperature parameter received from the temperature sensor312 configured to measure temperature of the drive belt 206 or airtemperature of the CVT 122, the detection circuit 324 provides anearlier detection of the critical belt life event for avoiding anoverheat condition of the drive belt. Consequently, the longevity anddurability of the drive belt 206 may be increased.

In step 602, the monitoring circuit 322 receives and monitors theenvironmental condition parameters or signals from the sensor 160, suchas the temperature signal from the temperature sensor 312 configured tomeasure temperature of vehicle components, e.g., the drive belt 206 orthe air intake or exhaust system 124, 126 of the CVT 122. For example, adrive belt temperature or a CVT air outlet temperature is measured byone or more temperature sensors 312.

In step 604, the monitoring circuit 322 receives and monitors the atleast one engine-based parameter related to the engine load signal, thethrottle position signal, the engine torque signal, the engine powersignal, or the like. Other exemplary engine-based parameters includeparameters related to a clutch ratio, a gear selection or position ofthe transmission, an intake pressure, an intake temperature, a drivelinespeed, an ECU clock, and the like, as received from each correspondingsensor 160.

In step 606, the monitoring circuit 322 receives and monitors the atleast one driveline-based parameter, such as the vehicle speed parameterfrom the vehicle speed sensor 316 or the engine speed parameter from theengine speed sensor 318. In certain embodiments, a wheel speed sensor isalso used to monitor the speed parameter.

In step 608, the detection circuit 324 detects the critical belt lifeevent based on a comparison of at least one of the engine-based,driveline-based, and environmental condition parameters with apredetermined threshold for predicting a remaining life of the drivebelt 206 of the CVT 122. When the at least one of the engine-based,driveline-based, and environmental condition parameters is greater thanthe predetermined threshold, control proceeds to at least one of step612 and step 614. Otherwise, control returns to steps 602, 604, and 606.

For example only, the critical belt life event F(life) may be defined bya function of time and at least one of the engine-based,driveline-based, and environmental parameters, as provided by expression(2):F(life)=Remainer−T·Parm  (2)

wherein T denotes a time period, Parm denotes the at least one of theengine-based, driveline-based, and environmental condition parameters,and Remainer denotes a remaining life time period left for the drivebelt 206. As an example, the critical belt life event may be detected bythe detection circuit 324 when the belt temperature exceeding apredetermined threshold (e.g., greater than 250° F.) continues for apredetermined time period (e.g., 10-15 minutes), or a remaining life ofthe drive belt 206 is less than a minimum life time threshold. In oneembodiment, the minimum life time threshold is determined by at leastone of a belt temperature, a belt speed, and a belt load. As an exampleonly, when the belt temperature is at 250° F. for 15 minutes, theremaining life time period is approximately 150 hours, but when the belttemperature is at 330° F. for 10 minutes, the remaining life time periodis approximately 10 hours. The belt temperature (or the belt speed orload) and the belt life time period have an inverse relationship such asa negative exponential slope on a graph. As such, the remaining lifetime period can also be similarly calculated based on the belt speed andthe belt load to suit different applications. As such, a thermaldegradation of the drive belt 206 is predicted by the detection circuit324.

In step 610, when the detection circuit 324 detects that the remaininglife of the drive belt 206 is less than the minimum life time threshold(e.g., 10% remaining life left), control proceeds to at least one ofstep 612 and step 614 (or simultaneously to both steps 312 and 314)depending on the application. Otherwise, control returns to steps 602,604, and 606.

In step 612, the alert circuit 326 generates the information signal INFObased on the detected triggering event to inform the user using thedisplay 165. For example, the information signal INFO is displayed bythe display circuit 330 using a dashboard light or an audible signalincluding a textual or graphical indicator (e.g., ° F./° C. belttemperature reached (or to be reached), miles-to-belt-failure, % beltlife remaining, or % belt life used) on the display 165, requestingmaintenance of the drive belt 206. Other suitable audio, visual, ortactile indicators are also contemplated.

In step 614, the alert circuit 326 automatically adjusts or modifies atleast one of the operating parameters, such as the environmentalcondition parameters, the engine-based parameters, or thedriveline-based parameters, based on the calibration table 334 stored inthe database 304 to prevent or lessen the potential CVT drive beltfailure. For example, when the detection circuit 324 identifies thecritical belt life event, the alert circuit 326 automatically reducesthe vehicle speed by a predetermined value. Other suitable adjustmentsor modifications of the operating parameters are contemplated to suitdifferent applications.

FIG. 7 illustrates an exemplary processing sequence of an enginecrankshaft acceleration variation event detection logic 700 of thediagnostic system 300. The engine crankshaft acceleration variationevent is one of the triggering events detected by the detection circuit324, and is triggered based on a variation pattern of at least oneoperating parameter measured during a predetermined time period. It iscontemplated that the parameter variation pattern is monitored anddetected based on historical information of a comparative logic oralgorithm.

During operation, the engine crankshaft acceleration variation event maybe perceived to be caused by the belt slipping event described above, oran improper firing sequence event of the power source 106. Enginecrankshaft acceleration variation event detection logic 700distinguishes the belt slipping event from an engine combustion misfireevent. Thus, it is advantageous that the present method improves thediagnosis of the fault of the drive belt 206 without regard to acombustion misfire signal.

In step 702, the monitoring circuit 322 receives and monitors theenvironmental condition parameter or signal from the vehicle 100, suchas a fuel state signal (e.g., fuel ON/OFF) from the fuel sensor 320 oran engine coolant temperature signal from the temperature sensor 312.Other exemplary environmental condition signals include a drive belttemperature signal, a clutch state signal, or the like. For example, theclutch state signal may indicate a fully engaged state, a partiallyengaged state, or a non-engaged state. Also, a sheave position signalmay be used as one of the environmental condition signals.

In one embodiment, the belt slipping event can be ignored within apredetermined tolerance range when the crankshaft acceleration signal isless than a predetermined lower threshold. However, the belt slippingevent cannot be ignored when the crankshaft acceleration signal isgreater than a predetermined upper threshold (i.e., when the vehicle orengine speed reaches a predetermined threshold), and the vehicle 100 isdecelerating from a current speed down to a lesser speed. If the fuelstate signal is OFF during the deceleration, an initial predeterminedtime period may be the best time period for which the belt slippingevent can be detected.

In step 704, the monitoring circuit 322 receives and monitors the atleast one engine-based parameter related to the crankshaft accelerationsignal, the engine torque signal, the transmission gear position signal,or the like. Other exemplary engine-based parameters include parametersrelated to a clutch ratio, a gear selection or position, an intakepressure, an intake temperature, a driveline speed, an ECU clock, andthe like, as received from each corresponding sensor 160.

In step 706, the monitoring circuit 322 receives and monitors the atleast one driveline-based parameter, such as the vehicle speed parameterfrom the vehicle speed sensor 316 or the engine speed parameter from theengine speed sensor 318. In one embodiment, a wheel speed signalreceived from the wheel speed sensor is also used to monitor the speedparameter.

In step 708, the detection circuit 324 detects the engine crankshaftacceleration variation event based on a variation pattern of at leastone operating parameter measured during a predetermined time period. Forexample, the engine crankshaft acceleration variation event is detectedby measuring an acceleration or deceleration rate of the crankshaftacceleration signal based on a crankshaft rotation angle (e.g., at each90°, 180°, or 270°). When a time-windowed acceleration or decelerationrate of the crankshaft acceleration signal is greater than apredetermined threshold, an initial detection of the variation patternis recognized by the detection circuit 324. In one embodiment, thetime-windowed acceleration or deceleration rate is not needed to bemeasured in an entire cycle of the engine.

In step 710, after the initial detection of the variation pattern, thedetection circuit 324 records or stores data related to the variationpattern at a predetermined time interval (e.g., at each engine cycle) inthe database 304 for subsequent comparison. In step 712, when afrequency of the variation pattern is greater than a predeterminedthreshold, the variation pattern lasts longer than a predetermined timeperiod, or any combination of the frequency and the pattern time periodis greater than a predetermined threshold (or time period), controlproceeds to at least one of step 714 and step 716. Otherwise, controlreturns to steps 702, 704, and 706.

For example only, the engine crankshaft acceleration variation eventF(ecav) may be defined by a function of parameter variation pattern,time period (or frequency) and at least one of the engine-based,driveline-based, and environmental parameters, as provided by expression(3):F(ecav)=Pattern−(T|Freq)·Parm  (3)

wherein Pattern denotes a parameter variation pattern, T denotes a timeperiod, Freq denotes a frequency of the parameter variation pattern, andParm denotes the at least one of the engine-based, driveline-based, andenvironmental condition parameters. In one embodiment, when apredetermined variation pattern of the crankshaft acceleration signal isdetected, and the detected variation pattern lasts for a predeterminedtime period, or repeats a predetermined number of times, the enginecrankshaft acceleration variation event is detected by the detectioncircuit 324. For example, when the engine is in an off throttle or zerofueling event, during a 1 second deceleration time period, the enginemay be reducing speed from 3500 to 2500 RPM. In this case, an undamagedbelt would have approximately 100 detectable engine compression orinertially induced crank shaft accelerations or decelerations. Incontrast, a belt with a damaged section would have approximately anadditional 8 to 30 detectable crankshaft acceleration or decelerations.

It is preferred that the alert circuit 326 selectively performs step 714or 716 depending on the application. Specifically, in step 714, when asingle occurrence of the engine crankshaft acceleration variation eventis detected, the alert circuit 326 performs a first or fast correctionmethod for determining whether the engine crankshaft accelerationvariation event is caused by the belt slipping event or the enginecombustion misfire event. In one embodiment, the time-windowedacceleration or deceleration rate is determined based on a vehiclespeed, a transmission state, a coolant temperature, and a clutch state.

As an example only, when the engine crankshaft acceleration variationevent is detected during a shorter time period (e.g., 2-10 milliseconds)and the fuel state signal is OFF or the engine speed is low (e.g., 100RPM), the engine combustion misfire event is not occurring but the beltslipping event is in progress. In another embodiment, when the enginecrankshaft acceleration variation event is detected and a negativetorque is detected, when the engine is producing less torque thanrequired to idle, the vehicle 100 is decelerating. During thedeceleration, if the drive belt 206 is not fully engaged, the beltslipping event is likely to occur. Thus, it is advantageous that theaccurate diagnosis of the exact cause of the engine crankshaftacceleration variation event is achieved by the first or fast correctionmethod.

In step 716, when a plurality of occurrences of the engine crankshaftacceleration variation events are detected, the alert circuit 326performs a second or slow correction method for determining whether theengine crankshaft acceleration variation event is caused by the beltslipping event or the engine combustion misfire event. For example, whenmultiple engine crankshaft acceleration variation events are detectedduring a longer time period (e.g., 2-60 seconds) (alternatively, thetime period may be a couple of minutes) and the engine torque is highduring the time period, the belt slipping event is in progress, not theengine combustion misfire event. In one embodiment, the belt slippingevent is investigated based on scenarios wherein one of fuel off, lowtorque, and high torque are identified. During a fuel off scenario, ifthere is a variation in the crankshaft signal then the engine crankshaftacceleration variation event is classified as a belt slipping event.During a low torque scenario, if a magnitude variation in crankshaftsignal is above a certain threshold then the engine crankshaftacceleration variation event is classified as a belt slipping event.During a high engine torque scenario, the engine crankshaft accelerationvariation event will be classified as an engine combustion misfireevent. In one example, if the engine crankshaft acceleration variationevent cannot be classified as a belt slipping event, it is classified asan engine combustion misfire event. In one example, if an enginecombustion misfire event is found, then the fuel injector to thecylinder that has misfired is deactivated. As with the first correctionmethod, it is advantageous that the accurate diagnosis of the enginecrankshaft acceleration variation event is achieved by the second orslow correction method.

In step 718, the alert circuit 326 generates the information signal INFObased on the detected triggering event to inform the user using thedisplay 165. For example, the information signal INFO is displayed onthe display 165 for warning the user of an occurrence of the beltslipping event based on the detected engine crankshaft accelerationvariation events.

One example of an engine crankshaft acceleration variation event beingclassified as either a belt slipping event or an engine misfire event isprovided in FIG. 8. Turning to FIG. 8, an engine crankshaft accelerationvariation event detection logic 800 is provided.

Monitoring circuit 322 monitors an engine crank position value with aninput from an engine crank position sensor 802, an engine rpm value withan input from an engine rpm sensor 804, and a shiftable transmissioninput shaft rpm value with an input from a downstream rpm sensor 806, asrepresented by block 810. Exemplary downstream rpm sensors 806 arepositioned to determine the rotational speed of a shaft that ultimatelyis drive by the output shaft of the CVT such as an input shaft of a ashiftable transmission, a output shaft of the shiftable transmission, awheel speed sensor, and a half shaft. If the shaft being monitored bysensor 806 is the output shaft of a shiftable transmission or downstreamfrom a shiftable transmission, a gear position sensor 807 (see FIG. 8)is also included to indicate the gear ratio of the shiftabletransmission. Based on the monitored values, detection circuit 324,detects a crankshaft acceleration variation event, as represented byblock 812. The crankshaft acceleration variation event is detected bymeasuring an acceleration or deceleration rate of the crankshaftacceleration signal based on a crankshaft rotation angle (e.g., atincrements of rotation, such as every 1°, 2°, 5°, 10°, 30°, and 90°)which may be determined based on the engine crankshaft position sensor802 and the engine rpm sensor 804. Exemplary crankshaft accelerationvariation events include engine misfire events and CVT damaged beltevents, both of which exhibit a repeating pattern over time.

Processing sequence 800 determines an interaction frequency that wouldbe associated with a damaged CVT belt, as represented by block 814.Detection circuit 324 monitors for an observed time-windowedacceleration or deceleration rate of the crankshaft acceleration signal,as represented by block 816. If an observed crankshaft accelerationvariation event is detected, the frequency of the observed crankshaftacceleration variation event is compared to the determined interactionfrequency of a damaged CVT belt by alert circuit 326, as represented byblock 818. If the observed crankshaft acceleration variation eventfrequency is within a first threshold amount of the determinedinteraction frequency of a damaged CVT belt, the observed crankshaftacceleration variation event is classified as a CVT damaged belt event,as represented by block 820. Otherwise the observed crankshaftacceleration variation event is classified as an engine misfire event,as represented by block 822. In either case, alert circuit 326, providesan indication to the operator of the vehicle of the condition.Alternatively, in the case of an engine misfire event, the fuel to thecylinder which is misfiring is stopped or the fuel and spark to thecylinder which is misfiring is stopped. The provision of fuel or fueland spark to the cylinder is reset at the next key restart of thevehicle.

In one embodiment, the first threshold amount is an absolute amount inHertz, such as 100 Hertz. In another embodiment, the first thresholdamount is a percentage amount. An exemplary percentage is within about10 percent above or below the determined interaction frequency of adamaged CVT belt. In embodiments, the observed crankshaft accelerationvariation event frequency is compared to both the determined interactionfrequency of a damaged CVT belt and to a multiple of the determinedinteraction frequency of a damaged CVT belt.

Referring to FIG. 9, an exemplary processing sequence 840 fordetermining the interaction frequency of a damaged CVT belt isillustrated. Detection circuit 324 detects the engine output speed(E_(SPEED)) from engine rpm sensor 804, as represented by block 842 anddetects the transmission input speed (T_(SPEED)) from transmission inputshaft rpm sensor 806, as represented by block 844. A CVT ratio(CVT_(RATIO)) of the CVT is determined based on the detected engineoutput speed and the transmission input speed, as represented by block846.

Based on the determined CVT ratio (CVT_(RATIO)) and the detected engineoutput speed (E_(SPEED)), a pitch diameter (DP_(DIAMETER)) of driveclutch 202 of CVT 200 is determined, as represented by block 848. Thepitch diameter (DP_(DIAMETER)) corresponds to the diameter on driveclutch 202 that drive belt 206 is riding upon. As is understood in theart, the spacing between the sheaves 208, 210 is adjustable resulting indrive clutch 202 having many possible pitch diameters. In one example,diagnostic circuit 302 references a lookup table 850 provided indatabase 304 to determine the pitch diameter of drive clutch 202.Diagnostic circuit 302 provides the determined CVT ratio (CVT_(RATIO))and detected engine speed (E_(SPEED)) as inputs to the lookup table 850,which returns a pitch diameter (DP_(DIAMETER)) associated with theprovided determined CVT ratio (CVT_(RATIO)) and detected engine speed(E_(SPEED)). In one example, diagnostic circuit 302 selects a pitchdiameter (DP_(DIAMETER)) from lookup table 850 that has the closestcorresponding determined CVT ratio (CVT_(RATIO)) and detected enginespeed (E_(SPEED)).

Based on the determined pitch diameter (DP_(DIAMETER)), diagnosticcircuit 302 determines a linear belt speed of CVT belt 206(BELT_(SPEED)), as represented by block 852. The linear belt speed ofCVT belt 206 (BELT_(SPEED)) and a known length of CVT belt 206, are usedby diagnostic circuit 302 to determine an interaction frequency(BELT_(FREQ)) of a point on CVT belt 206 with drive clutch 202, asrepresented by block 854. If CVT belt 206 has a damaged area, thedamaged area will interact with drive clutch 202 at the determinedfrequency from block 854 referred to as the interaction frequency of adamaged CVT belt (BELT_(FREQ)). Exemplary belt damages include spin burndamage, a missing cog on the CVT belt, and a cord pop-out.

Referring to FIG. 10, an exemplary processing sequence 900 isillustrated. Processing sequence 900 adjusts a peak output power of apower source 10 based on a determination that excessive energy isaccumulating within CVT 200.

Diagnostic circuit 302 determines an amount of energy input into CVT 200(E_(IN)), as represented by block 902. Diagnostic circuit 302 furtherdetermines an amount of thermal energy exiting CVT 200 (E_(OUT)), asrepresented by block 904. In one embodiment, the energy input into CVT200 is determined based on mechanical efficiencies of the CVT andmechanical power put into CVT 200 while the energy exiting the CVT isdetermined based on thermal characteristics of the air flowing throughCVT 200.

Diagnostic circuit 302 compares the energy into CVT 200 (E_(IN)) and thethermal energy exiting CVT 200 (E_(OUT)) to determine if energy isaccumulating within CVT 200, as represented by block 906. Energyaccumulating within CVT 200 results in a rise in the temperature of belt206 of CVT 200. Energy is accumulating within CVT 200 when (E_(OUT)) isless than (E_(IN)).

If energy is accumulating within CVT 200, diagnostic circuit 302compares the amount of accumulated energy to a threshold level, asrepresented in block 908. If the amount of accumulated energy exceedsthe threshold level, diagnostic circuit 302 causes a reduction in theenergy put into CVT 200 (E_(IN)), as represented by block 910, such asby reducing the peak output power of the power source 106 or the peakoutput torque of the power source 106. In one embodiment, the reductionin peak output power of power source 106 is gradual to avoid a rapiddecline in the peak output power of power source 106.

To cause the reduction in peak output power of power source 106diagnostic circuit 302 sends a message to the ECC 162 of power source106. An exemplary message is a CAN message over a CAN network bus.Alternatively, if diagnostic circuit 302 is part of ECC 162 asillustrated in FIG. 3, diagnostic circuit 302 directly limits the peakoutput power of power source 106.

Referring to FIG. 11, an exemplary processing sequence 930 fordetermining an amount of energy into CVT 200 (E_(IN)) is illustrated.Diagnostic circuit 302 determines the power source 106, illustrativelyan internal combustion engine, output power level (ENGINE_(POWER)), asrepresented by block 932. In one example, the output power level(ENGINE_(POWER)) is determined for example by engine calculated torqueoutput multiplied by the engine speed. Diagnostic circuit 302 thenretrieves a CVT clutch efficiency (CLUTCH_(EFFICIENCY)) from a CVTclutch efficiency map or lookup table 936, as represented by block 934.

The CVT clutch efficiency map has different efficiency values forcorresponding output power levels (ENGINE_(POWER)). In one example,diagnostic circuit 302 selects a CVT clutch efficiency(CLUTCH_(EFFICIENCY)) from lookup table 936 that has the closestcorresponding determined output power level (ENGINE_(POWER)). The CVTclutch efficiency is an estimate of the percentage of energy passingfrom the drive shaft 120 associated with CVT 200 to the driven shaft 128associated with CVT 200. The remainder of the energy is assumed to beretained in the interior of CVT 200 as heat. Diagnostic circuit 302determines the energy put into CVT 200 (E_(IN)) from the product(ENGINE_(POWER)) and the quantity of (1−CLUTCH_(EFFICIENCY)), asrepresented by block 938.

Referring to FIG. 12, an exemplary processing sequence 960 fordetermining an amount of energy out of CVT 200 (E_(OUT)) is illustrated.Diagnostic circuit 302 determines an air temperature of the air enteringthe interior of CVT 200 through air supply conduits 230, as representedby block 962. Based on this temperature reading and a heat transfercoefficient 966, diagnostic circuit 302 determines the amount of energyout of CVT 200 (E_(OUT)) based on a CVT clutch airflow model 968, asrepresented by block 964. The CVT clutch airflow model is based onengine speed (sensor 804), downstream driveline shaft speed (sensor806), gear position (sensor 807), and altitude of the vehicle. Thealtitude of the vehicle may be determined based on a barometric pressuremeasured by a barometric pressure sensor or based on a location valueprovided by a GPS system. In one embodiment, an exit temperature of theairflow in exhaust conduit 238 is also monitored and is used todetermine the energy out of the CVT 200.

The above detailed description and the examples described therein havebeen presented for the purposes of illustration and description only andnot for limitation. For example, the operations described can be done inany suitable manner. The methods can be performed in any suitable orderwhile still providing the described operation and results. It istherefore contemplated that the present embodiments cover any and allmodifications, variations, or equivalents that fall within the scope ofthe basic underlying principles disclosed above and claimed herein.Furthermore, while the above description describes hardware in the formof a processor executing code, hardware in the form of a state machine,or dedicated logic capable of producing the same effect, otherstructures are also contemplated.

What is claimed is:
 1. A vehicle diagnostic method of a vehicleincluding an internal combustion engine and a continuously variabletransmission (CVT) operatively coupled to the internal combustionengine, the method comprising the steps of: determining an amount ofinput energy provided to the CVT by the internal combustion engine;determining an amount of output thermal energy leaving the CVT;determining based on the amount of input energy and the amount of outputthermal energy an amount of accumulated energy in the CVT; comparing theamount of accumulated energy to a threshold; and altering the amount ofinput energy in response to the amount of accumulated energy satisfyingthe threshold.
 2. The diagnostic method of claim 1, wherein the step ofaltering the amount of input energy includes the step of altering atleast one of power and torque provided by the internal combustion engineto the CVT.
 3. The diagnostic method of claim 1, wherein the amount ofinput energy is determined based on mechanical input characteristics tothe CVT.
 4. The diagnostic method of claim 1, wherein the amount ofoutput thermal energy is determined based on fluid characteristics ofthe CVT.
 5. The diagnostic method of claim 1, wherein the step ofdetermining the amount of input energy provided to the CVT by theinternal combustion engine includes the steps of: determining an outputpower of the internal combustion engine; determining a CVT clutchefficiency based on the determined output power; and determining theamount of input energy provided to the CVT based on the determinedoutput power and the determined CVT clutch efficiency.
 6. The diagnosticmethod of claim 5, wherein the step of determining the CVT clutchefficiency based on the determined output power includes the step ofretrieving from a database the determined CVT clutch efficiency.
 7. Thediagnostic method of claim 1, wherein the step of determining the amountof output thermal energy leaving the CVT includes the steps of:determining an air temperature of air entering an interior of the CVT;and determining the amount of output thermal energy leaving the CVTbased on a CVT clutch airflow model, a heat transfer coefficient, andthe determined air temperature.
 8. The diagnostic method of claim 1,wherein the threshold is an absolute amount.
 9. The diagnostic method ofclaim 1, wherein the threshold is a percentage.
 10. The diagnosticmethod of claim 9, wherein the percentage is within approximately 10percent above or below a determined interaction frequency of a damagedCVT belt.
 11. The diagnostic method of claim 1, wherein the step ofaltering the amount of input energy in response to the amount ofaccumulated energy satisfying the threshold includes the step ofoverriding a user input.
 12. A vehicle diagnostic method of a vehicleincluding an internal combustion engine and a continuously variabletransmission (CVT) operatively coupled to the internal combustionengine, the method comprising the steps of: determining an amount ofaccumulated energy in the CVT; comparing the amount of accumulatedenergy to a threshold; and altering an amount of input energy providedto the CVT in response to the amount of accumulated energy satisfyingthe threshold.
 13. The diagnostic method of claim 12, wherein the stepof determining the amount of accumulated energy in the CVT includesdetermining a temperature of a belt of the CVT.
 14. The diagnosticmethod of claim 12, wherein the step of determining the amount ofaccumulated energy in the CVT includes the step of: determining theamount of input energy provided to the CVT by the internal combustionengine; determining an amount of output energy leaving the CVT; anddetermining a difference between the amount of output energy and theamount of input energy.
 15. The diagnostic method of claim 12, whereinthe step of altering the amount of input energy in response to theamount of accumulated energy satisfying the threshold includes the stepof overriding a user input.
 16. A vehicle diagnostic method of a vehicleincluding an internal combustion engine and a continuously variabletransmission (CVT) operatively coupled to the internal combustionengine, the method comprising the steps of: determining an amount ofinput energy provided to the CVT by the internal combustion engine;determining an amount of output thermal energy leaving the CVT;determining a difference between the amount of output thermal energy andthe amount of input energy; comparing the difference to a firstthreshold; determining a temperature of a belt of the CVT; comparing thetemperature of the belt to a second threshold; and altering the amountof input energy in response to at least one of the amount of accumulatedenergy satisfying the first threshold and the temperature of the beltsatisfying the second threshold.
 17. The diagnostic method of claim 16,wherein the step of altering the amount of input energy in response tothe at least one of the amount of accumulated energy satisfying thefirst threshold and the temperature of the belt satisfying the secondthreshold includes the step of overriding a user input.
 18. Thediagnostic method of claim 17, wherein at least one of the firstthreshold and the second threshold is an absolute amount.
 19. Thediagnostic method of claim 17, wherein at least one of the firstthreshold and the second threshold is a percentage.